The present invention relates generally to a position sensor for generating a position signal representing the relative position between two members movable relative to one another. More particularly, the present invention concerns a position sensor which is adapted for use as a height sensor in a computer controlled vehicle suspension system.
Various types of vehicle height sensors have been proposed. For example, U.S. Pat. No. 4,105,216 to Graham et al. discloses a vehicle height sensor which utilizes a pair of optical switches each comprising a light emitting diode (LED) and an associated photo transistor. A light shuttering arrangement is located between each LED and its respective photo transistor and is movable in response to relative movement between the sprung mass and unsprung mass of the vehicle. The optical switches generate logic signals representing whether the sprung mass of the vehicle is within a selected trim band, above the selected trim band, or below the selected trim band.
Other types of switching devices have also been proposed for use in vehicle height sensors which generate logic level output signals. U.S. Pat. No. 4,054,295 to Elliot discloses a position sensor which utilizes a pair of magnetic reed switches mounted on the sprung mass and responsive to a magnet movable with the unsprung mass. U.S. Pat. No. 4,236,074 to Chen discloses a vehicle height sensor which utilizes a pair of beta detectors mounted on the sprung mass for sensing the position of two radioactive material sources movable with the unsprung mass.
U.S. Pat. No. 4,310,172 to Claude et al. discloses a vehicle height sensor which utilized a pair of Hall effect switches as the switching devices. In one embodiment, magnets are located on a pair of followers attached for movement with the unsprung mass. A pair of Hall effect switches mounted for movement with the sprung mass detect the magnetic fields generated by the magnets and thereby the position of the followers to determine the relative position between the sprung and unsprung masses. In a second embodiment, the magnets and Hall effect switches are mounted on the sprung mass in spaced apart relationship. A pair of followers attached for movement with the unsprung mass are adapted to selectively interrupt the magnetic field between a magnet and the associated Hall effect switch to generate logic signals representative of the relative position between the sprung and unsprung masses.